1. Field of the Invention
This invention relates generally to a process for forming resinous composition surface coverings and more particularly to an "upside-down" process for forming such a product wherein a resinous dryblend layup is formed on a release carrier and heated to form a porous cohesive layer. Settable inks are applied to and set within the dryblend layer to create a design thereon which may extend through the thickness thereof from the back to the extent desired. A permanent carrier is then applied and the release carrier is removed. A deeply embossed multi-level decorative surface may be achieved on the product by brushing or otherwise removing the non-design carrying portions of the dryblend prior to the final fusion step.
2. Description of the Prior Art
It is known to enhance the appearance of plastic floor and wall coverings by means of various decorative designs thereon which may extend partially or entirely through the sheet. Further enhancement of the appearance of such sheets has been accomplished by achieving a three-dimensional appearance thereon. Prior methods of doing this have included mechanical or chemical embossing techniques or inclusion with the granules of the sheet-forming composition of an ingredient which can be subsequently removed or altered to produce an embossed effect. It is also known to form a decorative surface covering by applying a resinous coating to a releasable carrier, decorate the coating, apply the backing and then remove the releasable carrier and invert the product for use.
One method for producing a through-grained pattern on a flexible floor covering is shown by U.S. Pat. No. 592,186 wherein granular linoleum-forming material is preconsolidated on a backing sheet at a slightly elevated temperature to form a porous mass. The partially consolidated mass is then printed by means of printing blocks or rollers so that the colored or inlaid effect penetrates to a greater or lesser extent the substance of the linoleum. The sheet is then fully consolidated by heat and pressure.
U.S. Pat. No. 3,359,352 describes depositing a layer of fine granules of resinous composition on the surface of the base, heating to sinter the granules and form a porous layer, printing a design on the sintered layer with a printing composition which will penetrate into the porous composition and then, by heat, with or without pressure, forming the printed porous layer into a non-porous layer containing an inlaid design.
Copending U.S. Patent Application Ser. No. 483,971, filed June 28, 1974, in the name of Elvin M. Weidman, relates to a process for forming decorative smooth surfaced surface covering wherein a sintered resinous dryblend layer is formed on a releasable carrier. Settable resinous inks are then applied to selected surface areas thereof in overlapping relationship. The inks may penetrate completely or only partially through the dryblend layer and, after fusion of all of the resinous material, form clearly defined, in-register design areas which, after removal of the releasable carrier and inversion of the sheet, are visible from the wear surface which during processing was the surface which was in contact with the releasable substrate.
U.S. Pat. No. 3,804,657 relates to a process for producing a resinous composition surface covering having a multi-level decorative surface by depositing a layer of granular resinous dryblend on a backing sheet, heating the granules to form a porous cohesive layer therefrom, cooling the layer and applying settable resinous inks thereto to form a design thereon, gelling the ink, removing non-design carrying portions of the porous layer, and heating to fuse all of the remaining resinous material.
Another method of forming a decorated thermoplastic resinous sheet is shown by U.S. Pat. No. 2,874,416, wherein a thin layer of thermoplastic resin is applied to a carrier sheet, a design is printed on the resinous sheet before any film strength has developed therein; a body layer of a thermoplastic resin is applied over the printed design; the layers are fused by application of heat thereto; and, the resulting decorated sheet is stripped from the carrier.
U.S. Pat. No. 3,378,617 relates to a method of facing building products with exposed mineral granules wherein the mineral granules are deposited on and embedded up to their median plane in a layer of smaller inert particles which have been spread on a supporting surface. An inorganic binder is spread over the layer of granules and then the inert particles are removed from the spaces between the granules by brushing, for example, after the binder is set.
In the embodiment of the present invention relating to the formation of a multi-level decorative surface on resinous surface covering, the porous cohesive layer of dryblend is printed with settable resinous inks on what ultimately becomes the back of the sheet. The color of smallest area coverage is printed first and it may extend partway or substantially completely through the dryblend layer. The remaining colors which progressively increase in their area coverage are then printed thereover one on top of the other. These inks are also of predetermined viscosity and are applied in amounts predetermined to ensure the desired degree of penetration to the porous dryblend. The process of this invention may conveniently result in a thickness of the thinnest color area of about 10 to 15 mils. The other color areas may increase in their thickness up to the total thickness of the dryblend layer. Upon subsequent removal of the dryblend from the non-printed areas, the most elevated color areas will always be the thickest and, since all of the colors extend through to what will become the back of the final sheet, retention of the original pattern for the life of the surface covering is assured.